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EXHIBIT 99.1
1
DIAMOND OFFSHORE DRILLING, INC. RIG STATUS REPORT AS OF APRIL 11, 2005
<Table>
<Caption>
RIG NAME WD DESIGN LOCATION STATUS* OPERATOR CURRENT TERM
- -------- ----- ------------- --------- ---------- ---------------- -----------------
DOMESTIC DEEPWATER SEMISUBMERSIBLES(6)
Ocean Quest 3,500' Victory Class GOM Contracted Noble one well
Ocean Star 5,500' Victory Class GOM Contracted Kerr-McGee 220 day extension
Ocean America 5,500' Ocean Odyssey GOM Contracted Pioneer one assignment
well
Ocean Valiant 5,500' Ocean Odyssey GOM Contracted Kerr-McGee one well
Ocean Victory 5,500' Victory Class GOM Contracted Shell 100 day term plus
option
Ocean Confidence 7,500' DP Aker H- GOM Contracted BP five-year term
3.2 Modified
DOMESTIC 2ND/3RD GENERATION SEMISUBMERSIBLES(4)
Ocean Voyager 2,000' Victory Class GOM Contracted Walter Oil & Gas second of two
wells
Ocean Concord 2,200' F&G SS-2000 GOM Contracted ENI one well
Ocean Lexington 2,200' F&G SS-2000 GOM Contracted Walter Oil & Gas three wells
Ocean Saratoga 2,200' F&G SS-2000 GOM Contracted LLOG three wells
<Caption>
DAYRATE EST. END FUTURE CONTRACTS AND OTHER
RIG NAME (000S) START DATE DATE INFORMATION
- -------- --------- -------------- -------------- -----------------------------
DOMESTIC DEEPWATER SEMISUBMERSIBLES(6)
Ocean Quest low 100's early Feb. late May 2005 One well with Noble in high 110's beginning late May and ending mid
2005 June; followed by 120 day term plus option with Noble in mid 120's
beginning mid June and ending mid Oct. 2005. Available; actively
marketing.
Ocean Star mid 70's early Dec. mid July 2005 90 day term extension plus option with Kerr-McGee in low 140's
2004 beginning mid July 2005 and ending early Oct. 2005. Available; actively
marketing.
Ocean America low 130's late Mar. 2005 late April First of two well extension with Mariner in mid 110's beginning late
2005 April and ending early June; followed by first of three assignment
wells with Pioneer in low 150's beginning early June and ending late
Aug.; followed by second well with Mariner in low 130's beginning late
Aug. and ending late Sept.; followed by second and third of three well
extension with Mariner/Pioneer in low 150's beginning late Sept. and
ending late Nov. 2005. Available; actively marketing.
Ocean Valiant mid 80's late Jan. 2005 early May 2005 One well with Kerr-McGee in high 90's beginning early May and ending
mid July, followed by one well plus options with Kerr-McGee in low
130's beginning mid July and ending mid Sept. 2005; followed by 180 day
term extension with Kerr-McGee in low 150's beginning mid Sept. 2005
and ending mid Mar. 2006. Available; actively marketing.
Ocean Victory low 130's mid Feb. 2005 late May 2005 Available; actively marketing.
Ocean Confidence mid 170's early Jan. early Jan. Available; actively marketing.
2001 2006
DOMESTIC 2ND/3RD GENERATION SEMISUBMERSIBLES(4)
Ocean Voyager low 80's early April mid April 2005 One well with Walter in mid 110's beginning mid April and ending late
2005 April; followed by one well with ATP in mid 90's beginning late April
2005 and ending mid June; LOI for one well in low 110's beginning early
Aug. and ending late Sept.; followed by LOI for one well in low 110's
beginning late Sept. and ending mid Nov.; followed by two wells plus
option in mid 120's beginning mid Nov. 2005 and ending early Feb. 2006.
Available; actively marketing.
Ocean Concord mid 50's early Feb. mid April 2005 One well for Kerr-McGee in upper 50's beginning mid April and ending
2005 mid May 2005; followed by one well with Kerr-McGee in mid 70's
beginning mid May and ending mid July 2005; followed by two well
extension plus option with Kerr-McGee in mid 90's beginning mid July
and ending late Sept. 2005. Available; actively marketing.
Ocean Lexington mid 50's late Jan. 2005 late April Rig will go in for approximately 90-day Survey and maintenance between
2005 second and third well, beginning late April and ending late July.
Following survey, two additional wells with Walter in low 60's
beginning late July and ending late Sept.; followed by one well plus
option with Walter in low 80's beginning late Sept. and ending late
Oct. 2005. Available; actively marketing.
Ocean Saratoga mid 60's mid Dec. 2004 early July Two wells plus option with LLOG in low 110's beginning mid July and
2005 ending mid Dec.; followed by six month extension with LLOG in low 120's
beginning mid Dec. 2005 and ending mid June 2006. Available;
actively marketing.
</Table>
2
DIAMOND OFFSHORE DRILLING, INC. RIG STATUS REPORT AS OF APRIL 11, 2005
<Table>
<Caption>
RIG NAME WD DESIGN LOCATION STATUS* OPERATOR CURRENT TERM
- -------- ----- ------------- --------- ---------- ---------------- -----------------
DOMESTIC JACKUPS (12)
Ocean Crusader 200' Mat GOM Contracted Walter Oil & Gas two well
Cantilever extension
Ocean Drake 200' Mat GOM Contracted ADTI/Kerr-McGee one well
Cantilever extension
Ocean Champion 250' Mat Slot GOM Contracted Hunt two wells
Ocean Columbia 250' Independent GOM Contracted Kerr-McGee Five wells
Leg
Cantilever
Ocean Spartan 300' Independent GOM Contracted LLOG three wells plus
Leg option
Cantilever
Ocean Spur 300' Independent GOM Contracted Spinnaker one well
Leg
Cantilever
Ocean King 300' Independent GOM Contracted El Paso one well plus
Leg option
Cantilever
Ocean Nugget 300' Independent GOM Contracted Mariner one well
Leg
Cantilever
Ocean Summit 300' Independent GOM Contracted LLOG two wells plus
Leg option
Cantilever
Ocean Warwick 300' Independent GOM Contracted Newfield one well
Leg
Cantilever
Ocean Titan 350' Independent GOM Contracted BHP one well plus
Leg option
Cantilever
Ocean Tower 350' Independent GOM Contracted Chevron/Texaco one well plus
Leg option
Cantilever
<Caption>
DAYRATE EST. END FUTURE CONTRACTS AND OTHER
RIG NAME (000S) START DATE DATE INFORMATION
- -------- --------- -------------- -------------- -----------------------------
DOMESTIC JACKUPS (12)
Ocean Crusader mid 30's late Jan. 2005 early May 2005 Available; actively marketing.
Ocean Drake mid 40's early April mid April 2005 Two wells plus option with ADTI/CMI/Palace in low 40's beginning mid
2005 April and ending early May 2005. Available; actively marketing.
Ocean Champion low 40's late Jan. 2005 mid June 2005 Available; actively marketing.
Ocean Columbia mid 40's early Jan. mid June 2005 Available; actively marketing.
2005
Ocean Spartan high 40's late Feb. 2005 early June Available; actively marketing.
2005
Ocean Spur mid 40's mid Dec. 2004 late April One well with Forest in mid 40's beginning late April and ending early
2005 June 2005. Maintenance/repairs early June through late July 2005.
Available; actively marketing.
Ocean King mid 50's early Mar. mid April 2005 One well extension in mid 50's beginning mid April and ending early
2005 May; followed by one well extension plus option in mid 50's beginning
early May and ending early June; LOI for four wells plus option in low
60's beginning early July and ending late Nov. 2005. Available;
actively marketing.
Ocean Nugget low 50's early April early May 2005 Two wells plus option with Houston Exploration in low 50's beginning
2005 early May and ending mid Aug. 2005. Available; actively marketing.
Ocean Summit mid 40's late Feb. 2005 late May 2005 Available; actively marketing.
Ocean Warwick low 50's mid Mar. 2005 early May 2005 90 day term with Chevron/Texaco in high 40's (adjustable rate)
beginning early May and ending early Aug. 2005. Available; actively
marketing.
Ocean Titan mid 50's late Jan. 2005 mid May 2005 Two wells with Walter in mid 70's beginning mid May and ending mid
July; followed by one well extension with Walter in mid 70's beginning
mid July and ending mid Aug. 2005. Available; actively marketing.
Ocean Tower mid 50's early Jan. early July One well extension plus option with Chevron/Texaco in high 60's
2005 2005 beginning early July and ending mid Sept. 2005. Available; actively
marketing.
</Table>
3
DIAMOND OFFSHORE DRILLING, INC. RIG STATUS REPORT AS OF APRIL 11, 2005
<Table>
<Caption>
RIG NAME WD DESIGN LOCATION STATUS* OPERATOR CURRENT TERM
- -------- ----- ------------- --------- ---------- ---------------- -----------------
INTERNATIONAL SEMISUBMERSIBLES (17)
MEXICO
Ocean Ambassador 1,100' Bethlehem SS- GOM Contracted PEMEX four year term
2000 work
Ocean 1,500' Aker H-3 GOM Contracted PEMEX four year term
Whittington work
Ocean Worker 3,500' F&G 9500 GOM Contracted PEMEX four year term
Enhanced work
Pacesetter
Ocean Yorktown 2,850' F&G SS-2000 GOM Contracted PEMEX four year term
work
NORTH SEA
Ocean Nomad 1,200' Aker H-3 North Sea Contracted Talisman one year
Ocean Guardian 1,500' Earl & Wright North Sea Contracted Shell one year
Sedco 711
Series
Ocean Princess 1,500' Aker H-3 North Sea Contracted Talisman one year
extension
Ocean Vanguard 1,500' Bingo 3000 North Sea Shipyard DODI --
AUSTRALASIA
Ocean Bounty 1,500' Victory Class Australia Contracted ENI one well plus
option
Ocean Patriot 1,500' Bingo 3000 Australia Contracted Woodside two wells
Ocean Epoch 1,640' Korkut Shipyard DODI -- --
Ocean General 1,640' Korkut Viet Nam Contracted KNOC two wells
Ocean Baroness 7,000' Victory Class Indonesia Contracted Unocal 180 day extension
Ocean Rover 7,000' Victory Class Malaysia Contracted Murphy six option wells
<Caption>
DAYRATE EST. END FUTURE CONTRACTS AND OTHER
RIG NAME (000S) START DATE DATE INFORMATION
- -------- --------- -------------- -------------- -----------------------------
INTERNATIONAL SEMISUBMERSIBLES (17)
MEXICO
Ocean Ambassador mid 50's late July 2003 mid Dec. 2007 Available.
Ocean low 60's late July 2003 early Oct. Available.
Whittington 2006
Ocean Worker high 60's mid Aug. 2003 late July 2007 Available.
Ocean Yorktown mid 40's late Oct. 2003 mid July 2007 Available.
NORTH SEA
Ocean Nomad low 80's early Jan. early Jan. Available; actively marketing.
2005 2006
Ocean Guardian high 40's late Mar. 2004 late Mar. 2005 One year program with Shell in U.K. North Sea in low 80's beginning
late Mar. 2005 and ending late Mar. 2006. Available; actively
marketing.
Ocean Princess low 80's early Jan. late Dec. 2005 Available; actively marketing.
2005
Ocean Vanguard -- -- -- In yard for additional storm damage repairs. Est. completion late April
2005. One year plus option program in Norway with Statoil in low 140's
beginning in late April 2005 and ending in late April 2006. Available;
actively marketing.
AUSTRALASIA
Ocean Bounty mid 80's early April mid May 2005 One well plus option with ConocoPhillips in mid 80's beginning mid May
2005 and ending early Aug.; followed by one well with Coogee Res. in mid
80's beginning early Aug. and ending early Sept.; followed by LOI for
two wells plus option in low 90's beginning early Sept. and ending mid
Nov.; followed by LOI for one well plus option in mid 90's beginning
mid Nov. and ending mid Dec.; followed by LOI for four wells plus
option in high 90's beginning mid Dec. 2005 and ending mid June 2006.
Available; actively marketing.
Ocean Patriot high 70's mid Mar. 2005 mid April 2005 Two wells plus option with Santos in high 70's beginning mid April and
ending late June; followed by LOI for one well plus three options in
high 70's beginning late June and ending early Aug.; followed by one
well with Santos in high 70's beginning early Aug. and ending late Aug.
2005. Available; actively marketing.
Ocean Epoch -- -- -- Singapore shipyard preping for Murphy contract until mid April. Six
wells plus option with Murphy in low 70's in Malaysia beginning mid
April 2005 and ending late Dec. 2005. Available; actively marketing.
Ocean General mid 50's early April mid May 2005 LOI for four wells plus option in mid 70's in Malaysia beginning mid
2005 May and ending early Oct.; followed by LOI for two wells plus option in
high 70's in Viet Nam beginning early Oct. and ending late Dec. 2005.
Available; actively marketing.
Ocean Baroness mid 130's late Dec. 2004 early May 2005 Lump sum mobe to GOM beginning early May and ending early Oct.,
including prep; followed by LOI with Amerada Hess for one-year term
plus mobe in low 200's in GOM beginning early Oct. 2005 and ending
early Oct. 2006. Available; actively marketing.
Ocean Rover low 120's late Jan. 2005 mid July 2005 LOI with Murphy for 950 day extension at average dayrate in mid 170's
beginning mid July 2005 and ending mid Feb. 2008. Available; actively
marketing.
</Table>
DIAMOND OFFSHORE DRILLING, INC. RIG STATUS REPORT AS OF APRIL 11, 2005
<Table>
<Caption>
RIG NAME WD DESIGN LOCATION STATUS* OPERATOR CURRENT TERM
- -------- ----- ------------- --------- ---------- ---------------- -----------------
BRAZIL
Ocean Yatzy 3,300' DP DYVI Super Brazil Contracted Petrobras 700 day extension
Yatzy
Ocean Winner 3,500' Aker H-3 Brazil Contracted Petrobras 700 day extension
Ocean Alliance 5,000' Alliance Brazil Contracted Petrobras one year
Class extension
INTERNATIONAL DRILLSHIPS(1)
Ocean Clipper 7,500' DP Brazil Contracted Petrobras 700 day extension
Fluor/Mitsubishi
INTERNATIONAL JACKUPS(2)
Ocean Sovereign 250' Independent Mobing LOI DODI --
Leg
Cantilever
Ocean Heritage 300' Independent Mobing LOI DODI --
Leg
Cantilever
UPGRADE(1)
Ocean Endeavor 2,000' Victory Class Under tow Upgrading DODI --
COLD STACKED(1)
Ocean New Era 1,500' Korkut GOM Cold DODI --
Stacked
ASSET HELD FOR SALE(1)
Ocean Liberator 600' Aker H-3 S. Africa Cold DODI --
Stacked
PURCHASE PENDING -- RESERVED FOR UPGRADE(1)**
Garden Banks 2,200' Victory Class GOM Out of -- --
Service
<Caption>
DAYRATE EST. END FUTURE CONTRACTS AND OTHER
RIG NAME (000S) START DATE DATE INFORMATION
- -------- --------- -------------- -------------- -----------------------------
BRAZIL
Ocean Yatzy mid 70's early Nov. mid Oct. 2005 Available.
2003
Ocean Winner mid 50's early April mid Mar. 2006 Available.
2004
Ocean Alliance high 90's early Sept. early Sept. Available.
2004 2005
INTERNATIONAL DRILLSHIPS(1)
Ocean Clipper low 100's early Jan. early Mar. Available; actively marketing.
2003 2006
INTERNATIONAL JACKUPS(2)
Ocean Sovereign -- -- -- LOI for 190 days plus option in high 70's beginning late April and
ending early Nov. 2005. Lump sum demobe from Bangladesh to Indonesia
beginning mid April and ending late April. Available; actively
marketing.
Ocean Heritage -- -- -- Lump sum demobe to Qatar late Mar. until mid April; followed by
shipyard mid April until early May; followed by LOI for two wells plus
option in mid 70's beginning early May 2005 and ending late Jan. 2006.
Available; actively marketing.
UPGRADE(1)
Ocean Endeavor -- -- -- Mobing to Singapore shipyard for upgrade to 10,000 ft. capable 5th
Generation rig. Estimated completion early 2007. Available; actively
marketing.
COLD STACKED(1)
Ocean New Era -- -- -- Cold stacked Dec. '02.
ASSET HELD FOR SALE(1)
Ocean Liberator -- -- -- Cold stacked Nov. '02.
PURCHASE PENDING -- RESERVED FOR UPGRADE(1)
Garden Banks -- -- -- Currently retired from active service as drilling and production
platform.
</Table>
NOTES:
* GENERALLY, RIG UTILIZATION RATES APPROACH 95-98% DURING CONTRACTED PERIODS;
HOWEVER, UTILIZATION RATES CAN BE ADVERSELY IMPACTED BY ADDITIONAL DOWNTIME DUE
TO UNSCHEDULED REPAIRS AND MAINTENANCE, WEATHER CONDITIONS AND OTHER FACTORS.
** Diamond Offshore Services Company has entered into a definitive agreement to
purchase the Garden Banks, subject to certain conditions, which is expected to
be consummated in September 2005, and does not currently own the rig.
GOM = Gulf of Mexico